Signal repeaters are used to repeat a signal from a transmitter to a receiver, when the receiver is located too far from the transmitter to provide for reliable transmission; or, alternately, the receiver is positioned relative to the transmitter to limit the transmission for at least a portion of the time.
Certain repeaters are configured to use one antenna for both transmitting and receiving their signals. This use of a single antenna generally reduces the cost and the weight of the repeater. Reducing the weight of the repeater can permit a launch of a satellite based repeater with a smaller rocket. One difficulty with such repeaters is that unintended spurious output signals are produced in addition to the primary (intended) output signals. Even though any spurious output signal may be considered as noise, and as noise is undesirable; repeaters which provide spurious outputs with amplitudes which do not decay at a sufficient rate produce a particularly undesirable situation.
One example of a single antenna repeater is illustrated in U.S. Pat. No. 3,983,482, issued Sep. 28, 1976 to Doherty. This device is not usable in high gain application because it oscillates. This invention provides no capability for continuous wave signals. There is also a requirement to detect an input signal (or triggering from a receiver) to make the above repeater alter to the transmit mode.
Another example of a single antenna repeater is illustrated in U.S. Pat. No. 5,107,267, issued Apr. 21, 1992 to Janusas et al. This repeater is band limited to 500 MHz due to the sampling circuit in the receiver. This device also encodes the output for decoding, identification, scrambling, and jamming by another receiver. There is a switch (12) which is required to be repositioned between a receive position and a transmit position in order for the system to properly function.
It would be desirable to provide some technique, applicable to single antenna repeaters, which increases the rate of decay of spurious signal amplitude over time with the repeater being operable over a wide band-width. It would be desirable to provide a relatively straight-forward construction for such a repeater. It is the goal of the present disclosure to provide such a system.